How does acetylcholine influence the hippocampus?

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Patient H.M. and short-term memory loss explained — hippocampus Learn about Henry Molaison (better known as “patient H.M.”), whose short-term memory loss following a lobotomy helped researchers to understand how brain structures are related to brain function.

The hippocampus receives cholinergic input—meaning it responds to the neurotransmitter acetylcholine—directly from the medial septum.1

This input plays a vital role in regulating the physiological state of the hippocampus. Specifically, the medial septum is responsible for establishing the theta rhythm, one of the critical oscillatory rhythms within the hippocampus. Research indicates that if this region or the associated theta rhythm is abolished, it significantly interferes with normal hippocampal function.1